1. Field of the Invention
The present invention generally relates to fasteners. More particularly, the present invention relates to a push pin fastener having an expandable body portion.
2. Discussion
Rivet fasteners exist in many shapes and sizes as is well known in the art. Rivets are typically used to join two or more objects by providing two retaining ends connected by a shaft which provides a clamp load connecting the respective objects. Rivets generally do not provide a significant amount of axial retention. Rather the retention ability of a rivet is supplied from the clamp force generated by the rivet ends.
A Christmas tree type fastener is also well known in the art. A Christmas tree fastener provides a series of fins capable of different levels of axial retention and grip abilities. The fins of a Christmas tree type fastener typically flex inward during application and retract outward once inserted, thereby creating an axial force which holds the respective members together. The amount of axial force a Christmas tree type fastener provides is predetermined by the fin characteristics. Once a Christmas tree type fastener is fully inserted, the fins cannot be influenced to increase the axial force and gripping ability.